Competitive Warranty Act - Amends the Clean Air Act to revise provisions which require manufacturers to warrant automobile emission control devices or systems. Requires manufacturers to offer such warranties to the ultimate purchaser as an option.

Requires each manufacturer to affix, and each dealer to maintain, on each motor vehicle manufactured after the model year 1984, a label indicating the full cost of applying to such new motor vehicle: (1) the warranty of the vehicle's and engine's compliance with applicable pollution control regulations; and (2) the optional warranty required to be offered for the emission control device or system. Authorizes the Administrator to permit a manufacturer to comply with such labeling requirement by disclosing such information on the label required under the Automobile Information Disclosure Act. Treats violations of the labeling requirement under this Act as violations of the Automobile Information Disclosure Act. Directs the Administrator to utilize the authorities of specified recordkeeping and reporting provisions of the Clean Air Act to verify the costs disclosed by each manufacturer.

Makes it a violation of the Clean Air Act for any person to place any false or misleading information on the label required under this Act.

Makes conforming amendments.